[R] How to stratify data with multiple group simultaneously with R ggplot2?

[Rui Barradas]

Às 07:21 de 08/06/2025, Luigi Marongiu escreveu:
> I would like to plot multivariate data with ggplot2. I have multiple
> groups that I need to account for: I have the `x` and `y` values, but
> the data must be stratified also by `w` and `z`. I can group by either
> `w` or `z`, but how can I group for both simultaneously?
> In essence, in the example below, the legend should have two columns
> (A and B) and five rows (which are already there since the data is
> stratified by w). There should be 10 colors.
> How can I do that?
> Thank you
> 
>>>>>>>
> ```
> df = data.frame(x = c(rep(1,5), rep(2,5), rep(3,5), rep(4,5)),
>                                  w = rep(letters[1:5],4),
>                                  z = c(rep(LETTERS[1],10), rep(LETTERS[2],10)),
>                                  y = rnorm(20),
>                                  stringsAsFactors = FALSE)
> library(ggplot2)
> ggplot(df, aes(x=x, y=y, colour=w, group=w)) +
>    geom_line(linewidth=2) +
>    ggtitle("A+B")
> ggplot(df[df$z=="A",], aes(x=x, y=y, colour=w, group=w)) +
>    geom_line(linewidth=2) +
>    ggtitle("A")
> ggplot(df[df$z=="B",], aes(x=x, y=y, colour=w, group=w)) +
>    geom_line(linewidth=2) +
>    ggtitle("B")
> ```
> 
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Hello,

You can use the 4th variable to define facets. Like this?


ggplot(df, aes(x=x, y=y, colour=w)) +
   geom_line(linewidth=2) +
   facet_wrap(~ z, scales = "free_x") +
   ggtitle("A+B")


Hope this helps,

Rui Barradas



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